--- a/ChangeLog	Sun May 01 11:44:51 2016 -0700
+++ b/ChangeLog	Sun May 01 12:10:37 2016 -0700
@@ -1,11 +1,16 @@
 2016-05-01  Paul Eggert  <eggert@cs.ucla.edu>
 
+	mktime: simplify DEBUG_MKTIME
+	* lib/mktime.c (DEBUG_MKTIME): Define to 0 if not defined.
+	Simplify later usage accordingly.
+
 	Port mktime_internal offset to unsigned time_t
 	This avoids some assumptions about wraparound arithmetic on
 	signed integer overflow.
 	* lib/mktime-internal.h (mktime_offset_t): New type.
 	(mktime_internal): Use it in decl.
 	* lib/mktime.c, lib/timegm.c (mktime_offset_t) [_LIBC]: New type.
+
 	* lib/mktime.c (__mktime_internal, localtime_offset):
 	* lib/timegm.c (timegm): Use it.
 	* m4/mktime.m4 (gl_TIME_T_IS_SIGNED): New macro.

--- a/lib/mktime.c	Sun May 01 11:44:51 2016 -0700
+++ b/lib/mktime.c	Sun May 01 12:10:37 2016 -0700
@@ -17,9 +17,11 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-/* Define this to have a standalone program to test this implementation of
+/* Define this to 1 to have a standalone program to test this implementation of
    mktime.  */
-/* #define DEBUG_MKTIME 1 */
+#ifndef DEBUG_MKTIME
+# define DEBUG_MKTIME 0
+#endif
 
 #ifndef _LIBC
 # include <config.h>
@@ -40,13 +42,13 @@
 #include <intprops.h>
 #include <verify.h>
 
-#if defined DEBUG_MKTIME && DEBUG_MKTIME
+#if DEBUG_MKTIME
 # include <stdio.h>
 # include <stdlib.h>
 /* Make it work even if the system's libc has its own mktime routine.  */
 # undef mktime
 # define mktime my_mktime
-#endif /* DEBUG_MKTIME */
+#endif
 
 /* Some of the code in this file assumes that signed integer overflow
    silently wraps around.  This assumption can't easily be programmed
@@ -545,7 +547,7 @@
 libc_hidden_weak (timelocal)
 #endif
 
-#if defined DEBUG_MKTIME && DEBUG_MKTIME
+#if DEBUG_MKTIME
 
 static int
 not_equal_tm (const struct tm *a, const struct tm *b)